Low travel switch mechanism mounting



Dec. 29, 1964 G. BURY 3,163,741

LOW TRAVEL SWITCH MECHANISM MOUNTING Filed Dec. 19, 1962 v L I A 62 INVEN TOR.

George Bur BY fMflW ATT'Y.

United States Patent Ofiice 3,163,741 Patented Dec. 29, 1964 3,163,741LOW TRAVEL SWITCH MECHANISM MOUNTING George Bury, Chicago, lll.,assignor to Illinois Tool Works Inc., Chicago, 111., a corporation ofDelaware Filed Dec. 19, 1962, Ser. No. 245,852 7 Claims. (Ci. 2ll0168)Thisinvention relates in general to electrical switches of the lowtravel type and more particularly to a switch mechanism of theaforenoted type wherein the movable contacts are located for actuationwithout the use of rivets or other similar fastening means.

This invention is an improvement to the type of switch structure shownin Patent No. 2,840,656 assigned to the same assignee. Switch mechanismswherein the actuating member is moved an extremely short distance areuseful and necessary in a great many diverse installations, and are ofparticular importance in control functions where movements of a partmust be stopped upon reaching a certain location, or when an operationsequence must be controlled by very small movements. One of the majorproblems in the prior art has been to obtain a very precise, reliable,low travel switch at a very economically satisfactory cost.

The switch in the aforenoted patent has been exceedingly efficacious inthat it provides ultraprecision, dimensional stability, and smallmovement differential coupled with an extremely long life, i.e., itmaybe cycled in excess of ten million times without failure. Theaforenoted switch of the patented type has also been very excellent inthat deadcentering and switch teasing have been eliminated. However,while the aforenoted switch represented an improvement in manufacturingcosts over prior art types, there are many riveting and fasteningoperations necessary to provide the aforenoted switch construction whichare eliminated by the instant invention which substantially reduces thecost thereof without eliminating the other advantages that accrue to theswitch construction.

More particularly, it is an object of this invention to provide anexceedingly economical, high precision switch of the low travel type.

It is a further object of this invention to provide a switch of theaforenoted type wherein the entire switch is assembled with only sevenparts, i.e., three terminal means, movable contact means, a two-partcasing, and a push button member, all rivets, screw fasteners, and thelike having been eliminated.

A still further object of this invention is to provide a movable contactmeans which is located and deformed into an operative position by simpleassembly of the two parts of the casing into their final assembledrelationship.

A still further object of this invention is to provide a snap switch ofthe low travel type wherein the moving switch arm and the springactuating means therefor are made from a single stamping, and the springarm and the switch actuating means are initially offset from one anotherand are held to a uniform length such that the spring means is heldunder stress by mounting the corresponding ends parallel with eachother.

Other and further objects and advantages of the present invention willbe apparent from the following description when taken in connection withthe accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view through the novel switchconstruction;

FIG. 2 is a perspective view, somewhat diagrammatic in form andpartially in section, showing the base portion of the switch casing;

FIG. 3 is a side elevational view of the movable contact means prior tothe assembly thereof;

FIG. 4 is a plan view taken along lines 44 of FIG. 3

of the movable contact means shown in FIG. 3 prior to the bending of theoutboard legs thereof;

FIG. 5 is a semidiagrammatic perspective view showing an alternatearrangement of locating and fixing the movable contact means on the baseof the switch; and

FIG. 6 is a view similar to FIG. 3 of the alternate embodiment ofmovable contact means shown in FIG. 5.

Turning now to the drawings, the switch It) essentially comprises atwo-part casing comprising a base portion 12 and a cover portion 14,there being three quickly attachable depending terminal means 16, 18 and20 extending through the base. The switch casing is preferably made ofammonia-free phenolic and is precision molded into desired shapes andprovides excellent protection against corrosion. At the upper end ofterminals 18 and 20, and interiorly of the chamber formed by the twoswitch halves 12 and 14 are fixed contact means 22 and 24 in the form offine silver insert contacts. It will be noted that the terminal means 18and 26 are configured so that the contacts 22 and 24 are disposed inspaced opposed relationship to each other. A movable contact means 26 isactuatable between the fixed contacts 22 and 24 by a suitable low travelpush button mechanism in the form of a molded button 28 as shall beexplained.

The base portion 12 is formed with a plurality of transverse throughapertures 30, 32 and 34 for quick locking receipt of the terminals 16,18 and 20. There are several ways of locking the terminals such as 16,18 and 20 into position in the apertures 30, 32 and 34, one convenientway being to form the terminals with shoulders 17, 19 and 21 whichcooperate with complementary shoulders in the through apertures 30, 32and 34 in a force fit relationship which locate and seat the respectiveterminals by a simple push-on relationship.

The base portion 12 is further formed with a vertically aligned portion36 as viewed in FIG. 1 adjacent to the outboard end of the base andassociated with the aperture 34. A pair of ramp portions 38 and 40 aredisposed at substantially right angles to portion 36, said ramps 38 and44 being spaced from each other by a central portion 42 which isdisposed at an acute angle to portion 36 for purposes hereinafterappearing. Inboard from the corner defined by the confluence of portions36-33 and 3fi-40 are a pair of raised shoulders or humps 44 and 46 whichcooperate with the movable contact means as shall be described. Arelatively open area is formed in the base portion, generally centrallythereof, to provide sufficient room for the various positions of themovable contact means 26 and to afford ease of entry of the fixedcontact terminal 18.

The movable contact means 26.comprises a stamped electrically conductiveresilient sheet material member, preferably of beryllium copper or thelike, having a central arm portion 48 and twospaced leg portions 50 and52 separated by blanked-out portions 49 and 51. As will be apparent, themovable contact means 26 is generally rectilinear in its original shape.The free end portion 54 is formed with a through aperture centrallythereof to receive an enlarged contact means 56. The spacings 49 and 51between the center arm 48 and two legs 50 and 52 adjacent to portion 54merge into bulbous apertures 53 and 55. It will be noted that apertures53 and 55 may be in the form of through circular apertures and arepreferably made by a circular drill having a diame'ter larger than thespacings 49 and 51 between the arms and the legs and preferably are donein a manner such that the center-line of the apertures 53 and 55 arelocated on an extension of the inboard edges of arms 50 and 52respectively. The circular apertures are then merged with the inboardedges to provide the bulbous appearance shown in plan view in FIG. 4. Ithas been found'thatthe aforenoted structure provides excellent stressrelief.

As can be seen in-FIGS. 3 and 4, the arm 48 and the two legs 50-52 areoffset from one another and further each is formed with the dependingangularly ofiset portions 58, 60 and 62 as shown. The portions 58, 60and 62 are of substantially identical length. FIG. 4 is not a trueunderside plan view of FIG. 3 as aforementioned, but rather is a viewprior to the bending of the legs 50 and 52' to the position shown inFIG. 3 along bend line 57. The centers of bulbous blankouts 53-55 arepreferably coincident with line 57. Thus, when the legs 50 and 52 arerepositioned coplanar with arm 58 in assembly, it will be noted that thearm 48 is shorter in length than the two legs 50 and 52. Thus, whendepending portions 58, 60 and 62 are made coplanar by the assemblyoperation to be described, the arms 50 and 52 assume a serpentinerelationship and stress the center arm 48. Due to this stressedrelationship of the center arm 48, a very small (on the order of .0005inch) movement of the plunger is operable to actuate the contact 56between its desired positions;

As was aforenoted, the two arms 50 and 52 are bent along line 57 andpreferably are deformed, prior to assembly, approximately 18 from theplane of arm 43 and portion 54 which are substantially coplanar.

The assembly of the switch is exceedingly simple. More particularly, theterminal 18 is first assembled to aperture 32 by simply inserting samefrom the top as vviewed in FIG. '2 into the force fit receiving aperturetherefor. Next the terminal 16 and contact means 26 may be assembled,it'being noted that the aperture 34 is large enough to accept the ends58, 60 and 62 of the movable contact means 26 when they are fittedsnugly against the top portion of the terminal 16. Then the terminal 20is assembled, the last step being assembly of the cover portion 14containing the movable button 28. As can be seen in FIG. 1, portions 64and 66 of the cover confine and accurately force the end portions 58, 60and 62 of the movable contact means 26 into assembled relation so thatthey snugly engage the terminal 16 and are confined against movement. Itwill be further appreciated that due to precision molding techniques,the movable contact means may be very accurately located within thecasing and that no form of rivets or the like is necessary to locate themovable contact means or to make the connection between terminal 16 andthe ends of the movable contact means. Thus, due to the assembly, thecontact means 26 is placed in stressed condition for actuation.

It will be apparent that the movable contact means end portions 58, 60and 62 may be disposed on the inboard side of terminal 16 adjacent tovertical surface 36. This construction, while not shown, is possiblewith both forms of movable contact means as shown in FIGS. 3-4 and FIG.6.

The embodiments shown in FIGS. 5 and 6 are substantially similar to theforegoing except that the terminal 16 for the movable contact means maybe formed with wing portions 68 and 70 which are initially flat and co-7 planar with the terminal 16, but then are bent around as shown in FIG.5 to confine and encapsulate portions 58, 60 and 62, the ends ofportions 58, 60 and 62 being formed with short offsets 72, 74 and 76which fit under the wing portions 68 and 70 in their final position asshown in FIG. 5.

In operation, a very slight movement of the push button 28 will causethe contact to snap over-center between the two fixed contacts 22 and24. The device is exceedingly simple to assemble, is very economical,and is of high precision nature without requiring expensivemanufacturing techniques. 7

The specific embodiments of the invention herein shown and described arefor purposes of exemplification only.

4 skilled in the art and are to be understood as forming a part of myinvention insofar as it follows in the spirit and scope of the appendedclaims.

What is claimed as the invention is:

l. A snap switch mechanism comprising a movable switch structure havingan elongated switch arm and a leg generally parallel thereto, each ofsaid arm and leg being formed with an end portion generally transverseto the respective elongated planes thereof, said leg being initiallyformed so-as to be slightly longer than said arm and both said arm andsaid leg tending. to be substantially fiat, means for maintaining acorresponding free end of said arm and of said leg in fixed relationshipto one another but free for movement, anchor means comprising terminalmeans engaging said transverse end portions and being operable tomaintain said transverse end portions of said arm and leg respectivelycoplanar and parallel to each other to thereby place said arm instressed form, said arm being placed in tension, said leg being placedin compression and assuming a serpentine shape, a fixed contact meanstoward and away from which said switch structure is snapable, anactuating member engageable with said switch structure for effecting asnapping action, and elec trical terminal means connected to said fixedcontact means. i

2. The snap switch mechanism set forth in claim 1 and further includinga second leg similar to said first mentioned leg, said first and secondlegs being integral with said arm and with one another at the free endsof said arm and legs, and said legs respectively lying on opposite sidesof said arm.

3. The switch structure set forth in claim 2 wherein said transverse endportions of said arm and legs are formed with a tip portion disposedgenerally parallel to the main body portion of said arm and legs, saidtip portion being engageable with said anchor means to further aid inthe positioning and location thereof in fixed relationship in theassembly.

4. A switch comprising casing means having first and second separablemembers fit'table together to define an interior chamber, button meanslocated in said first member and extending exteriorly thereof foractuation, a pair of quickly insertable fixed contact means havingterminals insertable in said second member of said casing and having acontact disposed so as to be in fixed spaced relationship to each other,movable contact means for said switch, third terminal means associatedwith said movable contact means also mounted on said second casingmember, said movable contact means comprising an arm and a pair ofspaced legs, each of which are elongated and have a contact carryingendand an anchored end, said arm and legs being coplanar at the contactcarrying end and integral with each other, said arm and said legs atsaid anchored end each being formed with portions transverse to the mainportions thereof, said arm being shorter than said legs whereby thetransverse portion thereof at the anchored end is, prior to assembly,located closer to said contact carrying end than said transverseportions of said legs, said movable contact means being assembled tosaid third terminal means by having the transverse portions thereofdisposed in coplanar relationship to said third terminal means and heldin said position by said third terminal means and portions of said firstand second members of said casing means, the location of said transverseportions in fixed coplanar relationship anchoring said arm and legs andsimultaneously placing said legs in compression and said arm in tensionwhereby said button when actuated engages said arm to cause the latterto snap between said fixed contact means.

5. The switch set forth in claim' 4 wherein said third terminal means isformed with wing portions which are bendable toward each other toencapsulate said transverse portions of said arm and legs of saidmovable contact means.

6. The switch structure set forth in claim 4 wherein said arm and legsare spaced from each other a predetermined distance throughout a majorextent of the length thereof, said arm and legs being integrally joinedadjacent to said contact carrying end and separated from each other bybulbous aperture portions having a diameter greater than saidpredetermined distance of spacing, the major portions of said arm andsaid legs being initially offset from each other, said arm beingcoplanar with said contact carrying end, said legs being offsetdownwardly from said arm, said legs being offset about a lineintersecting the bulbous aperture portions between said arm and saidlegs.

7. The switch structure set forth in claim 6 wherein said anchored endsof said arm and legs are formed with References Cited by the ExaminerUNITED STATES PATENTS 2,743,331 4/56 Lauder et a1 200*67 FOREIGN PATENTS85 3,951 11/60 Great Britain.

BERNARD A. GILHEANY, Primary Examiner. ROBERT K. SCHAEFER, Examiner.

1. A SNAP SWITCH MECHANISM COMPRISING A MOVABLE SWITCH STRUCTURE HAVINGAN ELONGATED SWITCH ARM AND A LEG GENERALLY PARALLEL THERETO, EACH OFSAID ARM AND LEG BEING FORMED WITH AN END PORTION GENERALLY TRANSVERSETO THE RESPECTIVE ELONGATED PLANES THEREOF, SAID LEG BEING INITIALLYFORMED SO AS TO BE SLIGHTLY LONGER THAN SAID ARM AND BOTH SAID ARM ANDSAID LEG TENDING TO BE SUBSTANTIALLY FLAT, MEANS FOR MAINTAINING ACORRESPONDING FREE END OF SAID ARM AND OF SAID LEG IN FIXED RELATIONSHIPTO ONE ANOTHER BUT FREE FOR MOVEMENT, ANCHOR MEANS COMPRISING TERMINALMEANS ENGAGING SAID TRANSVERSE END PORTIONS AND BEING OPERABLE TOMAINTAIN SAID TRANSVERSE END PORTIONS OF SAID ARM AND LEG RESPECTIVELYCOPLANAR AND PARALLEL TO EACH OTHER TO THEREBY PLACE SAID ARM INSTRESSED FORM, SAID ARM BEING PLACED IN TENSION, SAID LEG BEING PLACEDIN COMPRESSION AND ASSUMING A SERPENTINE SHAPE, A FIXED CONTACT MEANSTOWARD AND AWAY FROM WHICH SAID SWITCH STRUCTURE IS SNAPABLE, ANACTUATING MEMBER ENGAGEABLE WITH SAID SWITCH STRUCTURE FOR EFFECTING ASNAPPING ACTION, AND ELECTRICAL TERMINAL MEANS CONNECTED TO SAID FIXEDCONTACT MEANS.